Your old sofa - and much more - could be composted, say scientists

Polyurethane plastics used to make a host of products from furniture fillings to shoe soles, cable insulation and paints – and which can be difficult to recycle – could soon be degraded in compost heaps, thanks to a study at the University of Manchester.

Dr Geoff Robson and his team at the Faculty of Life Sciences have found that certain fungi can degrade the plastic in soil. Furthermore the rate of degradation increases when the volume of these fungi is increased or nutrients are added to the soil to boost the fungi’s activity.

They are now carrying out further studies to make sure the degradation of polyurethanes does not adversely affect the composting process or its products.

Dr Robson, whose Biotechnology and Biological Sciences Research Council (BBSRC) funded study is published in the Applied and Environmental Microbiology, said: “This is a significant finding. Polyurethanes are used to make many, many products and can take up a large amount of volume in landfill sites, which are rapidly running out of space. This makes it a major environmental pollutant.

“This study opens the possibility that fungi could be used to degrade these materials instead of dumping them into landfill sites.”

The team placed polyurethane pieces in soil containing fungi and bacteria. As the polyurethane, which is made from petroleum, degraded, the number of fungi increased as they digested the byproducts, showing that it was indeed the fungi that were breaking down the plastic.

Dr Robson added: “Fungi which naturally occur in soils have a remarkable capacity to degrade dead plants and animals, playing a pivotal and essential role in nutrient cycling in the environment. This study demonstrates some of these fungi also have the ability to degrade man-made polyurethanes.